Process for producing glossy coatings on earthenware and metal



PROCESS FQR PIEZQBUCING GLOSSY (GUAT- ENGS N AND METAL Al men Francois En land-at, @rly, France, assignor Scci des lllsines Chiini ues Rhone- Poulenc, Faris, .sranee, a French body corporate No 3; [application June 1, 194-8, No. 3il,5ll5. In France June 16, 194i? 2 Claims. (Cl. Ill-23) This invention relates to vitrifiable compcsihut are not in tenfed to limit the invention in tions and to the use such compositions. i these examples all concern The most fusible vitriflable mineral composic t-mich boric anhyrlride and lead tions at present vknown, and in tio of about 1:9, the inventicular in the ceramic industries, glaze at about 5 considered as being limited 500 C. or, at the very lowest, at 450 C 1 proportions, which have only It has now been found, and this forms the because they give the most fusible basis of the present invention, that compositions obtained by the fusion of coric acid or Example I boric anhydride and of lead. oxide in variable proportions can be employed as vitrifiable cornintimately m clI positions at much lower temperatures, in the Parts case of the most fusible compositions as low 9301350 3015:

280 C. It is stated in the literature that when such m are combined by fusion until compositions are slowly heated they have sof- J mlwgeneousg Whereafter the telling g i tempemulres whlcvh Vary m ture is run on" and crushed. The product thus 3 485 c-l1accordlng to me q prepared applied to a metal or ceramic sup- 1011 It P Been found however, f port and it is brought to a temperature of about such 90311395145191 In fact return to the Equld Z0 300 C. As soon as the formation of a glossy state at the said temperatures and th 13 "511% vitrified coating is observed, the article is rapidly action of the temperature f f to even withdrawn from the source of heat. The coata small extent they become devltrlfied and mg remains glossy when eooled' rapidly return to the solid. crystalline state.

In the present invention, use is made of this Emample H phenomenon in order to obtain glossy coatings Th re thoroughly mix d; on supports consisting of metal or the like Parts (glass, ceramics), and according to the present I 17 invention, therefore, a process for the produc- Linium 921 tion of a glossy coating on a support comprises Cobaltous carbonate 4 applying to the support a composition obtained by fusing together boric acid or boric anhydride and lead. oxide, heating the composition until This mixture is fused, run off and crushed as in the preceding example. When heated, it it vitrifies and then immediately withdrawing gives a glossy black waiting as scan as i the mated quppgrt from thn source of heag a peratnre of 23G-3G0 C. is reached and remains It has also been found that the liquid phase glassy 1133.456 0 Beyond which devitnfica" WW be stahiliwd l some eytam. i e the re tion sets in. In contrast, in a mixture containliic suite so I tum to the Solid qtatp may retaadpd by mg no cabal-tons carbonate the oevltrification .7" -.-1-- adding to the compositions small quantities or snbrty aher fusion third substances. Examples are alkaline phos- 40 Escample III nhates or the oxides of zinc, nickel cobalt, tin, r, i .h' re are there hl mire aluminum or silicon employed, either separately 5 y d g Parts or ll). combinationun the iorrn of chemically rystamsed b01118 acid 173 pure products or in the Iorm of natural minerals Mimum 92 1 containing these elements, Feldspar kaolin 23 u are particularly favourable agents for retarding ZQZI Q 2 the return to the solid state.

The optimum proportion of such stabilising Wh n sed, un Off and crushed as hereinbeagents between as and 5 prefgrably t fore described, such a mixture has a zone of pracb t 2%, fact, th favourable ti 1 th tical stability after fusion which ranges from 300 agent in reases i-{ h the pe -gentage which C. to 46$ clystaliises at about 400 and it is employed, but beyond a certain value it returns to the stable liquid state at about 450 brings about a rise in the melting point. (3., whereas when no stabilising agents are em- The following ex in which parts ployed the matting consequent upon crystallisaare by weight, serve to illustrate the invention 55 tion follows shortly after fusion at 300 C.

Example IV Parts Boric acid 17.8 Minium 92.1 Tin oxide 2 When treated as hereinbefore described, the mixture melts at 300 C. and commences to recrystallise at about 350 C. (in the absence of tin oxide, crystallisation follows shortly after fusion at 300 C.) It then melts in stable fashion at about 450 C.

Example V There are thoroughly mixed:

Parts Hydrated boric acid 17.8 Minium 92.1 Kaolin 4 The ingredients are fused until completely homogeneous and the resulting composition is run off and cooled. The composition is then crushed and applied to a suitable support. Upon heating, it is found that a glossy and stable coating is formed as soon at a temperature of 300 C. is reached, and this coating can be brought to higher temperatures without destroying the gloss of the coating. In contrast. a similar mixture which does not contain any kaolin is devitrified as soon as it is heated to a temperature slightly 7 above 300 C.

on supports selected from the class consisting of earthenware and metal supports, which comprises applying to the support a layer of a composition consisting to the extent of at least by weight of a particulate fused mixture of lead oxide and boric oxide substantially in the proportion of 9 parts by weight of the former to 1 part by weight of the latter, heating the composition up to the temperature at which it first vitrifies and then immediately withdrawing the coated support from the source of heat.

2. Process for the production of glossy coatings on supports selected from the class consisting of earthenware and metal supports, which comprises applying to the support a layer of a particulate fused composition consisting to the extent of at least 95% by weight of a mixture of lead oxide and boric oxide and to the extent of 0.5 to 5% by weight of a stabilizing agent containing an oxide selected from the class consisting of the oxides of zinc, nickel, cobalt, tin, aluminum and silicon, the ratio of boric oxide to lead oxide in the composition being of the order of 1:9, heating the support thus coated up to the temperature at which the composition first vitrifies and then immediately withdrawingthe coated support from the source of heat.

AYMON FRANCOIS MAX-CLAUDET.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

1. PROCESS FOR THE PRODUCTION OF GLOSSY COATINGS ON SUPPORTS SELECTED FROM THE CLASS CONSISTING OF EARTHENWARE AND METAL SUPPORTS, WHICH COMPRISES APPLYING TO THE SUPPORT A LAYER OF A COMPOSITION CONSISTING TO THE EXTENT OF AT LEAST 95% BY WEIGHT OF A PARTICULATE FUSED MIXTURE OF LEAD OXIDE AND BORIC OXIDE SUBSTANTIALLY IN THE PRO-PORTION OF 9 PARTS BY WEIGHT OF THE FORMER TO 1 PART BY WEIGHT OF THE LATTER, HEATING THE COMPOSITION UP TO THE TEMPERATURE AT WHICH IT FIRST VITRIFIES AND THEN IMMEDIATELY WITHDRAWING THE COATED SUPPORT FORM THE SOURCE OF HEAT. 